1. Field of the Invention
The present invention relates to a composite plasmid, and particularly relates to a composite plasmid which is capable of propagating in Coryneform glutamic acid-producing bacteria.
2. Description of the Prior Art
Coryneform glutamic acid-producing bacteria belong to so-called "Coryneform bacteria", and are known to produce high amounts of L-glutamic acid. There are mutants of Coryneform glutamic acid-producing bacteria which produce other amino acids such as lysine; purine nucleotides such as inosine-5'-monophosphate, and other important fermentation products. Therefore, Coryneform glutamic acid-producing bacteria are of great importance to the fermentation industry.
The recently developed gene splicing techniques can successfully be applied for breeding or improving industrial microorganisms, especially in case of Escherichia coli. It has been difficult, however, to apply the gene splicing techniques for breeding or improving industrial microorganisms of Coryneform glutamic acid-producing bacteria, since suitable plasmid vectors useful for construction of such industrial microorganisms of Coryneform bacteria have not yet been developed.
Although several plasmids capable of propagating in Coryneform glutamic acid-producing bacteria have been found in Coryneform glutamic acid-producing bacteria, these plasmids have no inheritable characteristics which can be used as markers for easy identification. It is therefore still difficult to apply gene splicing techniques for breeding or improving industrial microorganisms of Coryneform glutamic acid-producing bacteria, even if multicopy plasmids isolated from the Coryneform glutamic acid-producing bacteria are used as the vectors.
A need, therefore, continues to exist for construction and development of a novel plasmid or vector useful for breeding or improving industrial microorganisms of Coryneform glutamic acid-producing bacteria.